1. Field of the Invention
The present invention relates to an electronic device, and in particular relates to power saving operations of a bridging device.
2. Description of the Related Art
Conventionally, a control chip is required between a host and an external peripheral device as a communication bridge, by which data are transferred between the host and the external peripheral device. The control chip may be an on-board chip on a motherboard of the host, or, the control chip may be placed on an add-on card assembled into an expansion slot of the host. For the on-board control chip, when the host is in a power-saving state (i.e., not in the normal operations) or a shutdown state, the on-board control chip still consumes some power. In another case wherein the control chip is deployed on an add-on card, note that no power is consumed by the control chip when the host is in a power-saving state or a shutdown state.
Ideally, when the host enters the power-saving state or the shutdown state, the host should output commands to the external peripheral device via the control chip to drive the external peripheral device to enter a power-saving state or to a shutdown state as well. However, the external peripheral device may fail to receive the commands for power saving or shutting down once the control chip loses its power (e.g. the control chip deployed on an add-on card). Thus, the on-going external peripheral device results in unnecessary waste of power.